As with any heavyweight let alone one as compact and with the screwdriver hook of a Marciano...Rocky would pretty much have a punchers chance but everything else is a literal uphill battle. With respect to the asterisk always attached to Lewis chin, Marciano would very much be in the same boat given Lewis jab and uppercut etc. 50 lbs is 50 lbs and when you walk in it multiples. Marciano looks to get in his chest literally and mentally but I can't help but see him sponging up bookoo damage while looking for the fight ender for his efforts.